1. Field of the Invention
This invention generally relates to measuring and testing electricity and, more particularly, to sensors, to probes, and to arrays of probes and sensors for detecting and for mapping electromagnetic fields.
2. Description of the Related Art
The mapping of electromagnetic field vectors is extremely difficult and complex. “Mapping” refers to describing the magnitude and direction of electromagnetic field vectors. Once the components of an electromagnetic field vector are known, electromagnetic fields may be expressed at a location and time. Electromagnetic fields, however, are often extremely complex to mathematically describe. Analysis of the electromagnetic field vector may require differentiation, integration, gradient, and divergence operations of vector components over lines, surfaces, and three-dimensional volumes. This analysis is considerably complicated when the line, surface, or volume is complexly shaped and cannot be described using mathematics. Electromagnetic field mapping is also used to detect and diagnose flaws in electrically conductive materials, such as cracks, corrosion, holes, or material inhomogeneities. Therefore, experimental measuring of electromagnetic fields is essential to map those fields produced by sources of complex geometries that are difficult to describe theoretically, or to detect fields that can be produced by unknown sources.
In general, a magnetic sensor is used to experimentally measure electromagnetic fields. The sensor is placed within the electromagnetic field and measurements are taken. There are, however, several problems with existing electromagnetic sensors. Although the prior art sensors may be designed to measure electromagnetic fields in one dimension, the prior art sensors are still sensitive to electromagnetic field vector components in other dimensions. Another problem is frequency dependence of existing inductive sensors. Many existing inductive sensors only have an adequate output over a preferred frequency range. If the frequency of the electromagnetic field lies outside the preferred frequency range, the sensitivity of existing inductive sensors are greatly reduced and measurements are lost or compromised. Thus, although sensors are often used to measure complex electromagnetic fields, these problems with existing sensor designs still present limitations in the measurement of electromagnetic fields.
There is, accordingly, a need in the art for improved electromagnetic sensors which substantially isolate individual components of electromagnetic field vectors, electromagnetic sensors which are sensitive over a wide range of frequencies, electromagnetic sensors with a compact design, electromagnetic sensors which are cost effective to manufacture and to use, and electromagnetic sensors that can be manufactured in two-dimensional and three-dimensional arrays.